First-principles investigation of the structural, elastic, electronic, and optical properties of semiconducting AgBr1–xIx (0 ≤ x ≤ 1) ternary alloys in rock-salt and zinc blende structures

Abstract

In this work, first principle calculations of the structural, electronic, elastic, and optical properties of novel AgBr1–xIx ternary alloys in rock-salt (B1) and zinc-blende (B3) structures are presented. The calculations were performed using the full-potential linear muffin-tin orbital (FP-LMTO) method within the framework of the density functional theory (DFT). The exchange and correlation potentials were treated according to the local density approximation (LDA). The lattice constants for the B1 and B3 phases versus iodide concentration (x) were found to deviate slightly from the linear relationship of Vegard’s law. The calculated electronic properties showed that AgBr1–xIx alloys in the B3 structure have a direct band gap (Γ – Γ) for all concentrations of x, which means that they can be used in long-wavelength optoelectronic applications, while in the B1 structure they have an indirect (Γ – R) band gap. The elastic constants Cij, shear modulus G, Young’s modulus E, Poisson’s ratio ν, index of ductility B/G, sound velocities vt, vl, and vm, and Debye temperature θD were also reported and analyzed. By incorporating the basic optical properties, we discussed the dielectric function, refractive index, optical reflectivity, absorption coefficient, and optical conductivity in terms of incident photon energy up to 13.5 eV. The present results were found to be in good agreement with the available experimental and other theoretical results.